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Implementation of Variable Threshold Dual Rate ADPCM Speech CODEC Considering the Background Noise (배경잡음을 고려한 가변임계값 Dual Rate ADPCM 음성 CODEC 구현)

  • Yang, Jae-Seok;Han, Kyong-Ho
    • Proceedings of the KIEE Conference
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    • pp.3166-3168
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    • 2000
  • This paper proposed variable threshold dual rate ADPCM coding method which is modified from the standard ADPCM of ITU G.726 for speech quality improvement. The speech quality of variable threshold dual rate ADPCM is better than single rate ADPCM at noisy environment without increasing the complexity by using ZCR(Zero Crossing Rate). In this case, ZCR is used to divide input signal samples into two categories(noisy & speech). The samples with higher ZCR is categorized as the noisy region and the samples with lower ZCR is categorized as the speech region. Noisy region uses higher threshold value to be compressed by 16Kbps for reduced bit rates and the speech region uses lower threshold value to be compressed by 40Kbps for improved speech quality. Comparing with the conventional ADPCM, which adapts the fixed coding rate. the proposed variable threshold dual rate ADPCM coding method improves noise character without increasing the bit rate. For real time applications, ZCR calculation was considered as a simple method to obtain the background noise information for preprocess of speech analysis such as FFT and the experiment showed that the simple calculation of ZCR can be used without complexity increase. Dual rate ADPCM can decrease the amount of transferred data efficiently without increasing complexity nor reducing speech quality. Therefore result of this paper can be applied for real-time speech application such as the internet phone or VoIP.

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A Study on Thermal Analysis of Dual Beam Laser Welding of Thin Metal Sheet (박판의 이중 빔 레이저 용접에서 열유동 해석에 관한 연구)

  • 김재웅
    • Journal of Welding and Joining
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    • v.15 no.4
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    • pp.99-108
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    • 1997
  • Analytical model for the temperature distribution and the cooling rate of weld in dual beam laser welding is presented for investigating the possibility of controling the cooling rate. The model is based on the solutions to the problem of heat flow due to the distributed and line heat sources for preheating and welding respectively in plates with finite thickness. The effects of beam power, beam distribution parameter, interbeam distance, and welding speed on the resulting temperature distribution and cooling rate are presented. The cooling rates of dual beam laser weld at the weld centerline under the investigated conditions are reduced to as one third of those of welds which were produced by single beam laser. And it appeared that the cooling rate of dual beam laser weld is strongly dependent on the process parameters of preheating laser beam power and welding speed.

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Factors Affecting the Experience of Dual Use of Conventional and heat-not-burn Tobacco among Adolescents with Smoking Experience: 14th(2018) Korean Youth Risk Behavior Survey (흡연경험이 있는 청소년들의 일반담배와 가열담배의 복합흡연경험 영향요인: 제14차 청소년건강행태조사를 기반으로)

  • Bin, Sung-Oh
    • The Journal of Korean Society for School & Community Health Education
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    • v.20 no.2
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    • pp.1-12
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    • 2019
  • Objectives: The purpose of this study is to understand the factors affecting the dual smoking experience of conventional and heat-not-burn tobacco among adolescents with smoking experience. Methods: The study selected 8,691 people with experience in smoking. Data analysis used SPSS 25.0. Logistic regression was performed to identify the factors affecting the dual smoking experience. Results: In this study, the dual smoking experience rate of conventional and heat-not-burn tobacco was 16.3%. The dual smoking experience rate was 5.09 times higher than the number of smokers among friends. The lower the smoking age, the higher the smoking rate, and the longer the smoking days, the higher the dual smoking rate of heat-not-burn cigarettes. Conclusion: We need a peer-to-peer group arbitration program rather than a separate anti-smoking arbitration program for smokers.

Dual-rate Digital Controller Design for Continuous-time Linear Systems

  • Park, Poo-Gyeon;Ko, Jeong-Wan
    • 제어로봇시스템학회:학술대회논문집
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    • pp.468-472
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    • 2003
  • The lifting technique is a standard control procedure that is commonly applied to dual-rate systems, where a critical difficulty is that care must be taken so that the resulting equivalent system preserves the causality constraint between the control signal and the measured output. To overcome this difficulty, the most attractive result has been suggested by defining control time sequences as the union of sample and hold time sequences. However, the sacrifice of regular control period scheme results in some serious disadvantages; restrictions on the implementation to hardware and the corresponding inefficient control scheme. On the contrary, this paper proposes a novel dual-rate control technique, which redescribes the system as a control-rate-based system having regular control period and designs the controller, with no causality constraint, through Linear Matrix Inequality (LMI) formulation.

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Real-time bias correction of Beaslesan dual-pol radar rain rate using the dual Kalman filter (듀얼칼만필터를 이용한 이중편파 레이더 강우의 실시간 편의보정)

  • Na, Wooyoung;Yoo, Chulsang
    • Journal of Korea Water Resources Association
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    • v.53 no.3
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    • pp.201-214
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    • 2020
  • This study proposes a bias correction method of dual-pol radar rain rate in real time using the dual Kalman filter. Unlike the conventional Kalman filter, the dual Kalman filter predicts state variables with two systems (state estimation system and model estimation system) at the same time. Bias of rain rate is corrected by applying the bias correction ratio to the rain rate estimate. The bias correction ratio is predicted from the state-space model of the dual Kalman filter. This method is applied to a storm event with long duration occurred in July 2016. Most of the bias correction ratios are estimated between 1 and 2, which indicates that the radar rain rate is underestimated than the ground rain rate. The AR (1) model is found to be appropriate for explaining the time series of the bias correction ratio. The time series of the bias correction ratio predicted by the dual Kalman filter shows a similar tendency to that of observation data. As the variability of the bias correction increases, the dual Kalman filter has better prediction performance than the Kalman filter. This study shows that the dual Kalman filter can be applied to the bias correction of radar rain rate, especially for long and heavy storm events.

Implementation of Dual Rate G.723 ADPCM Speech codec (16Kbps와 40Kbps의 Dual Rate G.723 ADPCM 음성 codec 구현)

  • Kim, Jae-Ohe;Han, Kyong-Ho
    • Proceedings of the KIEE Conference
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    • pp.2480-2482
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    • 1998
  • In this paper, the implementation of dual rate ADPCM using G.723 16Kbps and 40Kbps speech codec algorithm is handled. For small signals, the low rate 16Kbps coding algorithm shows the same SNR as the high rate 40Kbps coding algorithm, while the low rate 16Kbps coding algorithm shows the lower SNR than the high rate 40Kbps coding algorithm for large signal. To obtain the good trade-off between the data rate and synthesized speech quality, we applied low rate 16Kbps for the small signal and high rate 40Kbps for the large signal. Various threshold values determining the rate are tested for good trade off data rate and speech quality. Also the low pass filter effect of speech input and output devices is simulated at several cut-off frequencies. To simulation result shows the good speech quality at a low rate comparing with 16Kbps & 40Kbps.

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Design of Intelligent Digital Controller with Dual-Rate Sampling (듀얼 레이트를 갖는 지능형 디지털 제어기 설계)

  • Kim, Do-Wan;Joo, Young-Hoon;Park, Jin-Bae
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.559-562
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    • 2004
  • In this paper, a new dual-rate digital control technique for the Takagi-Sugeno (T-S) fuzzy system is suggested. The proposed method takes account of the stabilizablity of the discrete-time T-S fuzzy system at the fast-rate sampling points. Our main idea is to utilize the lifted control input. The proposed approach is to obtain the dual-rate discrete-time T-S fuzzy system by discretizing the overall dynamics of the T-S fuzzy system with the lifted control, and then to derive the sufficient conditions for the stabilization in the sense of the Lyapunov asymptotic stability for this system.

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Physical Layer Design of Dual-Band Guardian Modem based on Quasi-Orthogonal Code (유사 직교 부호 기반 이중 대역 Guardian 모뎀의 물리계층 설계)

  • Lee, Hyeon-Seok;Cho, Jin-Woong;Hong, Dae-Ki
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.1
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    • pp.127-132
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    • 2013
  • In this paper, we design the physical layer of Guardian modem for wireless public networks. The physical layer is composed of a dual-band RF (Radio Frequency) transceiver and a baseband-processor with quasi-orthogonal codes. The 2.4/5GHz dual-band RF transceiver can overcome the communication difficulty of dense 2.4GHz band for wireless public environment. Also the quasi-orthogonal code can reduce the required ASIC (Application Specific Integrated Circuit) design area. Finally, we analyze the performance of the developed system in viewpoint of data rate, BER (Bit Error Rate), PER (Packet Error Rate). Moreover we verify the performance of the dual-band RF communication.

The Optimal Composing the Filter-Bed for Coping with Daily Flow-Rate Fluctuation for the Performance of Sand Filtration Process (일유량 변동에 따른 여과수질 악화에 대처하기 위한 최적 여재구성에 관한 연구)

  • Park, Dong-Hak;Park, No-Suk;Kim, Seong-Su;Bae, Cheol-Ho;Jung, Nahm-Chung;Cjoi, Seung-II
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.4
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    • pp.485-491
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    • 2007
  • The fluctuation of inlet flow to a water treatment plant makes a serious problem that it can change the filtration rate abruptly, and ultimately occur the breakthrough of the detained particles inside filter media. Also, since it takes very short time (about 10 minutes) for the surface wave occurred from the fluctuation of inlet flow to reach the filtration process, it is impossible to control the filtration rate stably. Therefore, this study was conducted to evaluate the effect of daily flow-rate fluctuation on the performance of sand filtration process, and to suggest the dual media composition for coping with that effect. Comparative column tests have been carried out for various dual media (sand and anthracite) compositions. From the results of column tests, dual media, especially in the case of sand 45cm/anthracite 30cm, is more effective to cope with the effect of flow-rate fluctuation on the performance of filtration than single media (only sand). In addition, irrespective of dual media composition, managing ability to cope with that fluctuation tends to be weak at the end of allowable filtration duration time,

Coding Method of Variable Threshold Dual Rate ADPCM Speech Considering the Background Noise (배경 잡음환경에서 가변 임계값에 의한 Dual Rate ADPCM 음성 부호화 기법)

  • 한경호
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.17 no.6
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    • pp.154-159
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    • 2003
  • In this paper, we proposed variable threshold dual rate ADPCM coding method which adapts two coding rates of the standard ADPCM of ITU G.726 for speech quality improvement at a comparably low coding rates. The ZCR(Zero Crossing Rate) is computed for speecd data and under the noisy environment, noise data dominant region showed higher ZCR and speech data dominant region showed lower ZCR. The speech data with the higher ZCR is encoded by low coding rate for reduced coded data and the speech data with the lower ZCR is encoded by high coding rate for speech quality improvements. For coded data, 2 bits are assigned for low coding rate of 16[Kbps] and 5 bits are is assigned for high coding rate of 40[Kbps]. Through the simulation, the proposed idea is evaluated and shown that the variable dual rate ADPCM coding technique shows the qood speech quality at low coding rate.